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Thread: Surprise!

  1. #271
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    I do apologize for not reading through all of the 26 other pages....but I was just wondering if you were a big fan of Gomer Pyle and just wanted to hear the call to your boat over VHF..."Surprise, Surprise, Surprise..."

    Bob lives 3 doors down from me, so he can beat me personally, the rest of you don't need to get po'd.
    Respectfully, Thom

    SeaRail 19, SriRacha

  2. #272
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    May 2009
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    Power is power. The controller takes the voltage and converts it to an acceptable voltage for the battery. It doesn’t matter if it’s 22 volts or 17 volts. The 100watt panels in your example all produce 100 watts of energy. The controller is the key.
    Quote Originally Posted by robtryon View Post
    Hey Bob, I'm chuckling at your confusion because it's a confusing subject. Here is a little online calculator that may help: http://www.ohmslawcalculator.com/ohms-law-calculator For solar panels, there really is no rating convention. For example, 100-watt panels are popular. Manufacturers can easily "rate" a panel as 100W by adjusting the voltage it's rated at. If all panels were rated correctly (in my mind that would be 14.1V) then you could easily tell the output. So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.

    I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
    Last edited by WBChristie; 03-30-2020 at 08:06 PM.

  3. #273
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    Quote Originally Posted by Thom View Post
    I do apologize for not reading through all of the 26 other pages....but I was just wondering if you were a big fan of Gomer Pyle and just wanted to hear the call to your boat over VHF..."Surprise, Surprise, Surprise..."
    I've had the boat for awhile now and this still hadn't dawned on me - this is great! Here you go:

    https://www.youtube.com/watch?v=k5VZjT0JE70

  4. #274
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    I think the Sunpower panels are really good ones. I chose the Renogy panels for Amazon Prime shipping, quality of mfg and price point.
    I know of several returns on the Ronogy panels..... but at least I think they will be around to warranty their products. Unless the physical sizes are a factor there are few reason to buy anything but the Sunpower branded panel. 110w (not the 100 as it's voltage is lower) for <$250 from Amazon or others but you still need a backing. 7amps output using an MTTP.

  5. #275
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    So if you have a 100W panel that's rated at 17V and one rated at 22V, then the 17V would be more powerful.
    Hmmm..... its the opposite with an MTTP controller. You need the higher voltage since the controller is really a DC-DC converter. Same amps, more voltage = more power.

  6. #276
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    May 2009
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    No no no
    P=iv
    If the voltage is higher, then the amps are lower, and vice versa.
    Quote Originally Posted by solosailor View Post
    Hmmm..... its the opposite with an MTTP controller. You need the higher voltage since the controller is really a DC-DC converter. Same amps, more voltage = more power.
    Last edited by WBChristie; 03-31-2020 at 09:35 AM. Reason: grammar and spelling

  7. #277
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    Quote Originally Posted by WBChristie View Post
    No no no
    P=iv
    If the voltage is higher than the amps are lower, and vice versa.
    https://www.solar-electric.com/learn...trollers.html/

    More than you probably want to know about batteries and solar panels and how stupid they are---and the article actually doesn't discuss the different types of batteries today (lithium, PbAcid, AGM...) and different charge rates appropriate to the different batteries.
    Respectfully, Thom

    SeaRail 19, SriRacha

  8. #278
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    That looks like a good article, neighbor - I'll read it carefully.

    I already have the batteries so that's decided. The 110W SunPower panels and 160W Renogy panels are almost identical voltage but the 110W panels give me more placement options - and I'll probably go with three vs. four. Rob and I are currently (pun intended?) working on properly setting the new alternator regulator to optimally charge the new house bank. Then I'll re-focus on the solar charging.

    Solo, I plan to move the panels around on deck for optimal sun exposure, using ties to lash them down. There's enough deck area to avoid stepping on them. Do I still need backing in that case?

    At the end of the day these posts will hopefully be helpful to those reading this thread.
    .
    Last edited by BobJ; 03-31-2020 at 10:14 AM.

  9. #279
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    Yes, the panels are way to flex to even move carefully with no wind and at a minimum should have the twin wall polycarbonate backing.

    The 100W & 110W Sunpower panel are both rated at 5.9A @ 17.1V & 18.8V respectively so multiplying those you get 100&110W. However when using, for example the Victron MPPT controller, you need 5V delta to even start charging.... that 1.6V delta in panel output makes a big difference in actual output.

  10. #280
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    I'm reading this exchange re: solar panels and controllers with interest. I'd love to see a $$$ / amps generated comparison.
    S-2 7.9: "Wildcat of Loch Awe"
    1968 Selmer Series 9 B-flat and A clarinets
    1962Buesher "Aristocrat" tenor saxophone
    Piper One Design 24, Hull #35; "Alpha"

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